A slide member such as a slide bearing typically used in internal combustion engines for automobiles and industrial machines in general require high levels of seizure resistance, fatigue resistance, wear resistance and conformability. Some of the examples of slide bearings used in combustion engine applications are: an Al-based bearing lined with Al alloy over its back metal layer, a Cu-based bearing lined with Cu alloy over its back metal layer, and bearings with overlay coated on the surface of these alloy layers. The above described slide bearings are employed depending on the requirements of their use and environment.
Examples of overlay as such described above, are disclosed in Japanese Patent Publications such as JP H11-269580 A, and JP 2004-307960 A. The overlay disclosed in JP H11-269580 A employs Ag as a primary ingredient for improving seizure resistance. JP H11-269580 A also discloses Ag-based overlay comprising at least one of Cu, In, Sb, Al, and Sn amounting to a mass of 5% or less. Overlay disclosed in JP 2004-307960 A contains easily sulfurated metal particles having particle diameter of 1 μm or less and solid lubricant hard particles having particle diameter of 0.5 μm or less for the purpose of improving seizure, fatigue, and wear resistances. JP 2004-307960 A also discloses an Ag-based overlay containing easily sulfurated, metal particles, solid lubricant hard particles, and hard particles of carbides.
Recent internal combustion engines operate under high-speed and produce high-output in relatively less weight. However high-speed and high-output operation tends to thin the oil film to render the internal combustion engine seizure prone. On the other hand, reduced weight renders the bearing housing deformation prone, thus, rendering the slide bearing deformation prone and consequently fatigue prone. One solution to address such shortcomings is costing the base material with overlay consisting of Ag or Ag alloy having outstanding fatigue and wear resistances.
However, the downside of such overlay consisting of Ag or Ag alloy is hardness and inferior conformability relative to overlay comprising Sn, for example.